Why can people over 50 only get a flu shot and not the mist in the nose?

Approved by FDA: The studies done when the fda approved flunist by the drug manufacturer only included people up to 50 years old, so when the fda approved the drug, that was the approval it gave. More studies covering different age groups, are under way, but as of now, your doctor is not likely to make an exception for you if you are outside the approved age range and your insurance likely won't pay for it.

Testing requirements: The FluMist was tested only to 49, and was able to get approval for that. The question is whether it is effective enough compared to the shot, and whether there can be unintended consequences, such as giving the mist to a child with asthma. There would need to be further testing before the mist could be used in an older age group.

Testing/safety: The mist was approved only for specific age groups. These evolved when early testing revealed more potential for side effects in older/younger patients. The mist actually creates a mild infection at the lung tissue level to transfer into the blood. This can trigger bronchitis or set of asthma attacks. The limits are designed for the safety of the patients, not to exclude them.